1. Field of the Invention
The present invention concerns dielectric optical cables of the type having a core containing the optical fibers and peripheral reinforcements adapted to serve as armoring of the cable, together with a method of fabricating such cables.
2. Description of the Prior Art
Current optical cables, and principally buried dielectric cables, are armored with glass fibers or with reinforcements obtained by pultrusion so as to give them high resistance to traction and to crushing and to protect them from rodents in the case of buried cables. The reinforcements are made from a cross-linkable (heat setting) resin reinforced with long glass fibers (rovings). They are installed in the cable by means of a rotating cage, which is a slow operation that cannot be conducted in series with the extrusion of the sheath covering the cable.
Apart from the fact that the raw material used to obtain pultruded reinforcements is costly, a cable made in this manner has greater resistance to traction than it needs and that is not justified when it is to be buried.
Document EP-A-0 141 723 discloses an optical cable containing no metal materials and the central core of which comprising optical fibers is surrounded by an extruded protective tubular coating, an armoring and an extruded outer sheath. The armoring is made up of high mechanical strength wires that are laid up onto the protective coating or of fibers that do not have any resistance to compression that are disposed around the coating and stiffened by a binder.
The speeds at which the protective coating is extruded, the reinforcements are applied and the external sheath is extruded are made identical, which results in a relatively slow manufacturing process, quite apart from the fact that it is somewhat complex.
For this reason the aim of the invention is to provide an optical cable in which the reinforcements serving as armoring of the cable are extruded during fabrication of the cable.
Another aim of the invention is to provide a method of fabricating an optical cable that does not require a separate operation to apply the reinforcements.